Method of applying starch adhesive bonding agent

ABSTRACT

A method is disclosed for applying a starch adhesive bonding agent which is continuously circulated and heated to a temperature about 20*F below its gelatinization temperature. An applicator roll for applying the bonding agent is also heated by a circulation system so as to increase the temperature of any bonding agent on the roll to a desired temperature such as 2*F below gelatinization temperature.

United States Patent 11 1 [111 3,91 1,179 Goettsch Oct. 7, 1975 METHODOF APPLYING STARCH 3,750,746 8/1973 Norman 117/111 R ADHESIVE BONDINGAGENT Inventor: Walter J. Goettsch, Wilmette, Primary Examiner MichaelLusighan [73] Assignee: Molins Machine Company, Inc., Attorney, Agent,Firmseidel, Gonda &

Camden, NJ. Goldhammer [22] Filed: Mar. 20, 1974 21 Appl. No.: 452,876

[57] ABSTRACT Related US. Application Data Division Of 263,403, y 1972,A method is disclosed for applying a starch adhesive 38271395- bondingagent which is continuously circulated and heated to a temperature about20F below its gelatini- [52] US. Cl. 427/361; 1 18/5; 1 18/202; Zationtemperature An applicator roll for applying the 1 18/259; 1 18/602; 118/603; 427/366 bonding agent is also heated by a circulation system so51 11 1. c1. B44D 1/44 as to increase the temperature of any bondingagent [58] Fleld of Search 1 17/652, 1 l 1 R, 156; on the roll to adesired temperature Such as below 118/5, 202, 259, 602, 603; 427/361, 3lminization temperature.

[56] References Cited 5 Claims, 2 Drawing Figures US. Patent Oct. 7,1975Sheet2 0f2 3,911,179

F/Gl A9 SUPPL y TANK TEMP , --C0/VTROLLE/? HOL DING TANK METHOD OFAPPLYING STARCH ADHESIVE BONDING AGENT This application is a division ofcopending application Ser. No. 268,403, now U.S. Pat. No. 3,827,395dated Aug. 6, 1974.

This invention relates to a starch adhesive bonding agent applicatorsystem which is adaptable for use in a corrugator at the single facer orthe double facer glue machine. Each of these machines includes anadhesive applicator roll in contact with a source of starch adhesivebonding agent. A conventional starch adhesive bonding agent gelatinizesat a temperature of approximately l45-l60F, depending on variousadditives, and thereby becomes tacky so that it may act as an adhesive.

The adhesive circulation system includes means for continuouslycirculating the starch adhesive bonding agent at a temperature about 20Fbelow its gelatinization temperature. The heated bonding agent isapplied to a component layer of corrugated paperboard by means of aheated applicator roll.

The applicator roll is provided with a system of heating the same sothat it will further heat the previously heated adhesive bonding agentthereon to a desired temperature such as 2F below the gelatinizationtemperature. The various circulation systems are provided with controlsfor maintaining predetermined temperature levels which preferably do notdeviate by more than about 2F. In view of the fact that the applicatorrolls are heated, the previously heated adhesive bonding agent willincrease to a temperature such that very little subsequent heat input isrequired to gelatinize the adhesive bonding agent.

Many years ago, it was suggested that it would be advantageous tocirculate a starch adhesive bonding agent at a temperature slightlybelow its gelatinization temperature. See the article in PaperboardPackaging, pages 59, 60, March 1961. To my knowledge, no one hassucceeded in making a system work as proposed in said article. As apractical matter, it would be extremely difficult and expensive tocirculate a starch adhesive bonding agent at a temperature of 5 to l5Fbelow its gelatinization temperature as suggested in said article.

ln the present invention the starch adhesive bonding agent is drawn froma supply tank in a primary system maintained generally at a temperature25F to 40F below the gelatinization temperature of the bonding agent andtransmitted as required to a holding tank in a secondary system.

The starch adhesive bonding agent is circulated in the secondary systemby pump means and its temperature is raised by heating means to a levelapproximately F below the gelatinization temperature. For practicalreasons it is desirable to have as small a spread as possible betweenthe temperature of the adhesive in the secondary system and thegelatinization temperature, without incurring detrimental changes inadhesive viscosity. It should also be noted that the viscosity andtemperature sensitivity of different starch adhesives varies dependingon their formulation and that some starch adhesives can be successfullyutilized with a spread of less than 20F.

The increase in temperature of the adhesive bonding agent circulating inthe secondary system is effected principally by the relatively constantheat input from the heated applicator rolls. The heat exchangermodulates this heat input as demand for the bonding agent varies.

It is important that, regardless of variations in operating conditions,the temperature of the adhesive in the secondary system be held within12F of the desired level. It must also be understood that the normaloperation of a corrugating machine involves running at various speeds aswell as temporary shut-downs, and that these, in turn, cause appreciablevariations in adhesive demand or occasional complete cessation ofadhesive demand.

To maintain the temperature level of the adhesive in the secondarysystem when little or no new cooler adhesive is being added from theprimary system, cooling water is thermostatically circulated through theheat exchanger.

Circulation of the adhesive in the secondary system is maintained at auniform, relatively high flow rate, well above that normally used inexisting conventional systems. I have found that a flow rate in excessof 25 gallons per minute is needed for optimum operation of my system.

The idle speed of the applicator roll is also maintained at asubstantially higher rate. The applicator roll idling speed ispreferably to surface feet per minute.

The combination of the high flow rate of the adhesive bonding agent inthe secondary system, the stabilization of temperature level provided bythe thermostatically controlled heat exchanger and the high idling speedof the applicator roll provide the unexpected results achieved by myadhesive application system.

It is an object of the present invention to provide a novel method forapplying a starch adhesive bonding agent.

It is another object of the present invention to provide method forapplying starch adhesive bonding agent in a manner which requiresminimum heat input to gelatinize the agent while at the same time beingreliable and capable of adjustment.

Another object of this invention is to provide a starch adhesive bondingagent circulation method which has high flow rate at stable temperaturesabout 20 below the gelatinization temperature.

Other objects will appear hereinafter.

For the purpose of illustrating the invention, there is shown in thedrawings a form which is presently preferred; it being understood,however, that this invention is not limited to the precise arrangementsand instrumentalities shown.

FIGS. 1A and 1B illustrate a glue machine for use in practicing themethod of the present invention including circuitry associated therewithwhich has been illustrated schematically.

Referring to the drawing, wherein like numerals indicate like elements,there is shown a glue machine in accordance with the present inventiondesignated generally as 10. A supply tank 12 of a primary system isprovided for housing the supply of a starch adhesive bonding agent at atemperature in the range of about 100F to F. A pump 14 has its inletconnected to the supply tank 12. The outlet conduit 15 from the pump 14returns to the tank 12. Conduits 16, 18 and 20 are connected to conduit15.

Conduits 16 and 18 may be coupled to circuitry associated'with singlefacers. Conduit 20 is associated with the glue machine 10. Hence, onlythe circuitry associated with conduit will be described herein, with theunderstanding that similar type circuitry would be coupled to theconduits l6 and 18.

The conduit 20 is adapted to transmit the starch adhesive bonding agentto a holding tank 22 of a secondary system. Flow from conduit 20 intothe tank 22 is controlled by any suitable type valve and is preferably afloat-operated valve 24. In this manner, a uniform level of starchadhesive bonding agent may be automat ically maintained at apredetermined level to insure an adequate supply. Once the adhesivestarch bonding agent enters the tank 22, it never returns to the supplytank 12. It will be understood that the size of holding tank 22 issubstantially smaller than the size of supply tank 12.

The tank 22 is provided with an outlet conduit 26 containing a pump 28.Pump 28 may assume a wide variety of types. I prefer to use acommercially available pump having a large capacity such as to 40gallons per minute so as to effect a high flow rate in the secondarysystem.

Conduit 26 is connected to one end of the heat exchanger 30. The bondingagent flows through the heat exchanger 30 and exits therefrom by way ofconduit 32. Conduit 32 contains a shut-off valve to stop flow forservice shut-downs or wash-up, and is connected to the inlet of atray-like housing 36.

A conduit 34 is connected to conduit 32 and likewise has a shut-offvalve therein. Conduit 34 is connected to the inlet of a similartray-like housing 38. Housing 36 has an outlet connected to conduit 40.Housing 38 has an outlet connected to conduit 42. The conduits 40 and 42return the bonding agent to the holding tank 22.

While a pair of tray-like housings for the bonding agent is illustrated,it will be appreciated that more than two or only a single tray-likehousing may be utilized, if desired. It will be noted that a closedcirculation secondary system has been provided for the starch adhesivebonding agent beginning with the tank 22, from which the bonding agentis pumped under pressure through the heat exchanger 30, through one orboth of the housings 36, 38, and then returned to the tank 22. As thestarch adhesive bonding agent flows through the heat exchanger 30, itstemperature is raised to a temperature below its gelatinizationtemperature. As is well known to those skilled in the art, thegelatinization temperature of a particular formulation of starchadhesive will vary depending upon the ingredients thereof, such ascaustic soda.

As shown in FIG. 1A, there is provided a heater tank 44 containing asupply of water. A steam supply conduit 46 is connected to tank 44 andterminates therein as a coil 48. Steam exiting from the coil 48 bubblesupwardly through the water and heats the same. The temperature of thewater is detected by a thermostat 52 or other comparable temperaturedetector, which is connected to and controls a valve in conduit 46.

An outlet conduit 54 from the tank 44 contains a pump 56. Pump 56 forcesthe heated water under pressure through an adhesive applicator roll 58preferably of the gravure type.

A water supply conduit 60 has one end connected to the conduit 54. Theother end of conduit 60 is connected to the inlet of a similarapplicator roll 64. Conduit 60 contains a pump 62 which is similar topump 56. The applicator rolls 58 and 64 are heated by the water as itflows therethrough. The heated water supplied to the inlet of the hollowapplicator rolls 58 and 64 is at a temperature about 10F above thegelatinization temperature of the starch adhesive bonding agent so thatthe surface of the applicator rolls 58 and 64 will be at a propertemperature to raise the starch adhesive bonding agent thereon to atemperature about 2F below the gelatinization temperature thereof.

The applicator rolls 58 and 64 cause the temperature of the starchadhesive bonding agent in housings 36 and 38 to increase. To preventthis undesired increase in temperature which could cause prematuregelatinization during idling operation, the idling speed of the rolls 58and 64 is maintained at about 100 surface feet per minute. The conduit68 connects the outlet of applicator roll 64 to a distribution conduit70. Likewise, a conduit 66 connects the outlet of applicator roll 58 tothe distribution conduit 70.

Conduit 70 is comprised of two branches. One branch extends back to thetank 44 and contains a check valve 72. The other branch of conduit 70communicates with the jacket 78 of the heat exchanger 30 by way ofconduit 76. A valve 74, such as a solenoid operated valve, controls flowfrom conduit 70 to conduit 76. Valve 74 is controlled by a temperaturecontroller 82 which in turn has a thermocouple or other temperaturedetector 29 connected to the heat exchanger 30. Depending upon thedetected temperature of heat exchanger 30, the preheated water fromconduit 70 may flow through the jacket 78 of the heat exchanger.Alternatively, if the temperature of the bonding agent in heat exchanger30 is too high, valve 74 may permit cooler water to flow from conduit 84through conduit 76.

The outlet of the jacket 78 is connected to the tank 44 by way ofconduit 80. Conduit includes a temperature sensor 86 which controls avalve 88. Valve 88 will divert the circulating water to the tank 44 orto a drain 90 depending upon the temperature of the circulating water.If the circulating water is below a preset temperature, such as waterfrom conduit 84, it will be diverted by valve 88 to the drain 90.Otherwise, the recirculated water will be returned to the tank 44. Tank44 includes an overflow conduit 92 connected to a drain 94.

The operation of the invention is as follows. Since the complete systemincludes a dual closed circulation system for the starch adhesivebonding agent as well as a dual circulation system for the heated water,only a single system will be described hereinafter. It is assumed thatthe particular formulation of starch adhesive bonding agent gelatinizesat 145F.

Float control valve 24 maintains the level of the starch adhesivebonding agent in holding tank 22 at a predetermined level. As the starchadhesive bonding agent is consumed, additional make-up bonding agent isintroduced into tank 22 from tank 12 by way of conduit 20.

The starch adhesive bonding agent is pumped under pressure from tank 22at a high flow rate through the heat exchanger 30 which in combinationwith the heated applicator rolls raises and maintains the temperature ofthe bonding agent so as to be about 20F below the gelatinizationtemperature of the starch adhesive bonding agent, namely l27F. Thethusly heated starch adhesive bonding agent then flows through thehousing 36 and is returned by gravity to the tank 22 via conduit 40.

Heated water is pumped under pressure at a temperature of about 155Fthrough the applicator roll 58 and returned to the tank 44 via conduit70 or conduit 80.

, If the temperature of the bonding agent detected at the heat exchanger30 is below the predetermined temperature, controller 82 operates valve74 to permit some of the heated water in conduit 70 to flow through thejacket of the heat exchanger 30 to increase the temperature thereof.

Each of the applicator rolls is rotatably driven about its longitudinalaxis at a speed comparable to the speed of the paperboard which may be100 to 700 feet per minute. Applicator roll 58 applies the starchadhesive bonding agent from housing 36 to the crests of flutes onsingle-faced paperboard so that a liner may be adhesively bonded theretoin a double facer. In the double facer, the temperature of the starchadhesive bonding agent will be promptly increased about 2F so as togelatinize the bonding agent and effect a bond between the liner and thecrests of the flutes on the single-faced board, thereby makingdouble-faced paperboard.

This bond will then be strengthened by a further increase in temperaturewhich accelerates reduction of the water component of the starchadhesive bonding agent. This strengthening of the bond enables thedouble-faced (or multiwalled) paperboard to withstand the mechanicalstresses imposed by the subsequent slitting and scoring operation. Itmust be recognized that water loss prior to gelatinization isdetrimental since it results in a very poor bond or no bond whereaswater loss subsequent to gelatinization is helpful since it strengthensthe bond and thus permits increased operating speeds.

The applicator roll 58 is heated so that its peripheral surfacetemperature will increase the starch adhesive bonding agent thereon tothe predetermined temperature about 2 below gelatinization point. Whilethe hot water enters the roll 58 at a temperature of about 155F, due toradiation losses and contact with cooler adhesive the surface of roll 58will be about 143F. The thickness of the starch adhesive bonding agenton the applicator roll 58 may be controlled by a doctor blade or adoctor roll.

Caustic soda has been used as an ingredient in the starch adhesiveformulation heretofore to reduce water loss from the agent to the paperduring that period of time wherein the starch adhesive bonding agent isin contact with the paper, but is below the starch gelatinizationtemperature. The present invention reduces the length of time betweenapplication of adhesive bonding agent to the paperboard andgelatinization of the starch in the adhesive bonding agent, therebypermitting use of less caustic soda as an ingredient in the starchadhesive bonding agent formulation. This reduces some of the undesirableside effects of caustic soda, such as degradation of the adhesive.

It is to be emphasized that the capacity of the housing 36 is largerthan the capacity of holding tank 22. Further, the heat exchanger 30 isused to maintain the temperature of the starch adhesive bonding agent ata stable level about F below its gelatinization temperature through theentire secondary system. Any starch adhesive bonding agent which is notapplied by the applicator roll immediately flows through the housing 36and is returned to the holding tank 22. When the corrugating machine isidling and no lower temperature adhesive is being added to the secondarysystem, the high idling speed of to surface feet per minute of theapplicator roll prevents gelatinization of the bonding agent on thesurface of the roll. The heat exchanger 30 also cools the bonding agent,by using water from conduit 84, to offset heat applied to the bondingagent in the housings 36, 38 by the rolls. To maintain uniformity oftemperature level, all conduits in the secondary system are insulated.

Most of the heat required to raise the temperature of the starchadhesive bonding agent is furnished by the applicator rolls 58 and 64.The primary function of the heat exchanger 30 during operation is tomaintain the temperature of the bonding agent stable by heating orcooling the same as it flows therethrough. The high flow rate of thebonding agent creates turbulence in the housings 36 and 38 which has awashing effect on the surface of the applicator rolls to dislodge anypartially gelled particles thereon while at the same time reducesvariations in the surface temperature of the applicator rolls.

As a result of the structural interrelationship of the system disclosedherein, it is now possible to attain the advantages of more uniformpaperboard, shorter length of double-facer, reduction in consumption ofcaustic soda, increased film strength for starch adhesive, reduction inthe time that the starch adhesive bonding agent is in an ungelatinizedstate on the crests of the flutes of the single-faced paperboard whichdecreases the water loss to the paperboard, increased bond strength,more efficient heat utilization, and increased speed of production.

The present invention may be embodied in other specific forms withoutdeparting from the spirit or essential attributes thereof and,accordingly, reference should be made to the appended claims, ratherthan to the foregoing specification as indicating the scope of theinvention.

I claim:

1. A method for applying a starch adhesive bonding agent to a componentof a moving web of corrugated paperboard comprising providing a housingcontaining a supply of the bonding agent and an applicator rollassociated therewith for applying the bonding agent to said component,circulating the bonding agent at a rate of flow in excess of 25 gallonsper minute from a tank through said housing and back to said tank at auniform temperature about l5-20 F. below the gelatinization temperatureof the bonding agent, maintaining the temperature of the circulatingbonding agent stable at said uniform temperature by means of a heatexchanger between said tank and housing, heating said applicator roll sothat it will increase the temperature of the bonding agent on thesurface thereof from said uniform temperature to a temperature about 2F.below the gelatinization temperature of the starch adhesive bondingagent, and applying said bonding agent to said web by said applicatorroll.

2. A method in accordance with claim 1 including rotating saidapplicator roll at a speed corresponding to the speed of the web ofcorrugated paperboard while applying the bonding agent to the web ofcorrugated paperboard, and decreasing the speed of rotation of saidapplicator roll to about 70-l00 surface feet per minute when no web ofcorrugated paperboard is being fed.

3. A method in accordance with claim 1 including circulating heatedwater through said applicator roll at a temperature about 10F. above thegelatinization temperature of the starch adhesive bonding agent.

4. A method in accordance with claim 1 including providing a supply tankfor said bonding agent, withback to said tank at a uniform temperatureabout l5-20F. below the gelatinization temperature of said bondingagent, maintaining the temperature of said bonding agent stable at saiduniform temperature by means of a heat exchanger capable of adding to orsubtracting from the temperature of the bonding agent, and heating saidapplicator roll by flowing hot water therethrough so that it surfacetemperature will increase the temperature of said adhesive bonding agentfrom said uniform temperature to a temperature about several degreesbelow the gelatinization temperature of said bonding agent, and using atleast some of said hot water after flowing through said applicator rollto perform said maintaining step.

1. A METHOD FOR APPLYING A STARCH ADHESIVE BOUNDING AGENT TO COMPONENTOF A MOVING WEB OF CORRUGATE PAPERBORD COMPRISING PROVIDING A HOUSINGCONTAINING A SUPPLY OF THE BONDING AGENT AND AN APPLICATOR ROLLASSOCIATED THEREWITH FOR APPLYING THE BONDING AGENT TO SAID COMPONENT,CIRCULATING THE BONDING AGENT AT A RATE OF FLOW IN EXCESS OF 25 GALLONSPER MINUTE FROM A TANK THROUGH SAID HOUSING AND BACK TO SAID TANK AT AUNIFORM TEMPERATURE ABOUT 15*-20*F. BELOW THE GELATINIZATION TEMPERATUREOF THE BONDING AGENT, MAINTAINING THE TEMPERATURE OF THE CIRCULATINGBONDING AGENT STABLE AT SAID UNIFORM TEMPERATURE BY MEANS OF A HEATEXCHANGE BETWEEN SAID TANK AND HOUSING, HEATING SAID APPLICATOR ROLL SOTHAT IT WILL INCREASE THE TEMPERATURE OF THE BONDING AGENT ON THESURFACE THEREOF FROM SAID UNIFORM TEMPERATURE TO A TEMPERATURE ABOUT2*F. BELOW THE GELATININZATION TEMPERATURE OF THE STARCH ADHESIVEBONDING AGENT, AND APPLYING SAID BONDING AGENT TO SAID WEB BY SAIDAPPLICATOR ROLL.
 2. A method in accordance with claim 1 includingrotating said applicator roll at a speed corresponding to the speed ofthe web of corrugated paperboard while applying the bonding agent to theweb of corrugated paperboard, and decreasing the speed of rotation ofsaid applicator roll to about 70-100 surface feet per minute when no webof corrugated paperboard is being fed.
 3. A method in accordance withclaim 1 including circulating heated water through said applicator rollat a temperature about 10*F. above the gelatinization temperature of thestarch adhesive bonding agent.
 4. A method in accordance with claim 1including providing a supply tank for said bonding agent, withdrawingsaid bonding agent from said supply tank and delivering it to said firstmentioned tank in a manner which precludes return of said bonding agentfrom said first tank to said supply tank.
 5. A method for applying astarch adhesive bonding agent to corrugated paperboard comprisingproviding a housing containing a supply of adhesive bonding agent and anapplicator roll associated therewith for applying the bonding agent topaperboard, circulating the bonding agent at a rate of flow in excess of25 gallons per minute from a tank through said housing and back to saidtank at a uniform temperature about 15*-20* F. below the gelatinizationtemperature of said bonding agent, maintaining the temperature of saidbonding agent stable at said uniform temperature by means of a heatexchanger capable of adding to or subtracting from the temperature ofthe bonding agent, and heating said applicator roll by flowing hot watertherethrough so that it surface temperature will increase thetemperature of said adhesive bonding agent from said uniform temperatureto a temperature about several degrees below the gelatinizationtemperature of said bonding agent, and using at least some of said hotwater after flowing through said applicator roll to perform saidmaintaining step.